Hydraulic apparatus



lOct. 30, 1934. A F, MOODY 1,978,810

' HYDRAULIC APPARATUS Original F''led Feb. 28, 1928 2 Sheets-Sheet 2 Patented Oct. T30, 1934 HYDRAULIC APPARATUS Lewis Ferry Moody, Princeton, N. J.

Griginal application February 28, 1928, Serial No. 257,615. Divided and this application August 12, 1931, Serial No. 556,572

claims. (c1. 253-117) This invention relates to hydraulic apparatus and more particularly to draft tubes of hydraulic turbines. It has for certain of its objects to provide not onlyv an improved relation between the entrance and discharge passages of the draft tube but also to provide improved simplified forms of these passages and of the connection between the same whereby desirable characteristics of both .Q .the elbow and spreading types of draft tubes are had, thus obtaining eflicient deceleration of a regain of whirl energy in the uid while turning and conducting the samefrom the turbine runner in a relatively small and laterally confined space. Other objects and advantages will be apparent from the following description of the accompanying drawings, in which:

Fig. 1 is a section taken on line 1 1 of Fig. 2; Fig. 2 is a horizontal sectional View taken on Iline 2 2 of Fig. 1;

. employed with horizontal shaft turbines.

Fig. 3 is a vertical sectional View taken on line 3 3 of Fig. 2;

` Fig. 4 is a vertical sectional view on line 4 4 ofl Fig. 2; f

Fig. 5is a horizontal sectional view of a modiiication taken on line 5 5 of Fig. 6;

Fig. 6 is a vertical sectional view taken on lines 6 6 of Fig. 5;

Fig. 7 is a vertical sectional view taken on lines 7 7 of Fig. 5; and

Fig. 8 is a vertical sectional view taken' on line 8 8 of Fig. 5.

In' the drawings the various forms of draft tubes are shown as applicable to a vertical shaft turbine (not shown) although it will of course be understood that these draft tubes may also be It also Will be clear from the disclosure herein that the draft tubes may be used with any of the different types of turbines such as of the propeller or Francis type which are well-known and there- `fore need not be described or disclosed in detail.

It will suffice to say that the flow in leaving the turbine runner enters the entrance or primary passage 1 of the draft tube and from which the flow is turned and passes through a transition space somewhat in the nature of a spreading collector or transition passage 2 surrounding the entrance or primal portion of the draft tube and thence flows to tailwater. The primary passage as shown is formed of an outer wall having a slightly tapered conical or upper portion 4 gradually curved outward in a substantially horizontal direction at its lower end to form at least a partial bell-mouth 3. The primary draft tube serves to direct the iiow downward from the turbine runner and outwardly into a horizontal plane. The cross sectional area of this tube as shown increases gradually so as to give a gradual deceleration to the meridian components of the ow and at the same time the tube is adapted to handle efficiently flow containing whirling components about the turbine axis.

The passage 2 starts at the mouth of the draft tube, curving entirely around the axis of the draft tube and terminating in the horizontal straight discharge passage 5 having a direction downstream and radial to the draft tube. The outer wall of the transition passage is vertical as shown. f

The horizontal discharge passage 5 for discharging the direct ow from the collector passage 2 to tailwater is substantially rectangular in cross section, having a horizontal iioor 6 extending from the collector passage, lthe top or roof wall 6 of which is inclined upwardly at an angle of about 20 with the floor and substantially parallel vertical side Walls 7 and 8. Starting from the central portion of the top or roof 6 as shown at 9 in Fig. 4 the roof laterally Vslopes upwardly at a similar angle. While in this form the entrance passage is disposed symmetrically relative to the center of the discharge passage, instead of being offset, yet the bell-mouth is a surface of revolution except for the portion thereof eliminated by the intersecting substantially vertical upstream wall 2 of the horizontal passage.

In the embodiment of the invention illustrated in Figs. 5 to 8, the flow leaving the turbine runner enters the primary draft tube, which forms a vertical passage 10, is turned and passes through a collector or transition passage 11 concentric to the primary draft tube, and thence to tailwater. The primary draft tube as shown is formed of an outer wall 12 having a slightly tapered conical or upper portion 13, is gradually curved outward in a substantially horizontal direction at its lower end. Projecting upwardly from the floor 14 of the collector passage 11 into the flaring end of the wall 12 and concentric therewith is a cone 15, whose concave surface is formed in relation to the outline of the end wall 12. The outer wall 12 and cone 15, together form a primary draft tube which serves to direct the flow downward from the turbine runner and outward into a horizontal plane.

Collector passage 11 begins at the mouth of the draft tube and is concentric therewith, curving entirely around the axis of the draft tube and terminating in the horizontal straight discharge passage 16. The outer wall of the colmum height above the oor.

lector passage is vertical and its inner wall is formed by a portion of the cone 15.

The horizontal discharge passage 16 for discharge of the ow from the collector passage l1 to tailwater is substantially rectangular in cross section and has a floor 14 and a roof 17 inclined upwardly at an angle of approximately 20 with the floor. Vertical side walls 18 and 19 are substantially parallel. A pier or partition 20' divides the passage and supports the roof. downstream length of the discharge passage, is

restricted the angle of the top wall can be slightly4 increased, but should not be increased toov much to avoid loss of head and efficient deceleration. Starting from the central portion of the roof 17; the roof as shown at 21 in Fig. 8 alsotlaterally. slopes upwardly at an angle; of approximately 20. omitted as the occasion demands. In thismodification, as in the other, at least the initial' portion of the bell-mouth of the primary or entrance `passage extends substantially around 350. In

this form the bell-mouth is not intersected by the collector wall but instead the wall 23 commences at substantially the outer limits of the bell-mouth, that is, at thepoint where its outer and upper wall becomes horizontal and of mini- In each case `howeverfthe upstream wall is disposed suiiiciently upstream beyond the'bell-mouth so that the bellmouth has at least a portion extending upstream as in Fig` 1 or entirely upstream as in Fig. 6. Alsothe height of the discharge-passage at its "upstream end is not greater than the height of the lowermost portion of the bell-mouth.

In either case however the cross-sectional areas ofthe passagebefore, during and after passing around the bend are proportioned so ,as to effect the same velocity relations as set forth in my copending application Serial No, 257,615, filed February 28, 1928, Patent No. 1,853,138, which is directed generally to the form of draft tube-having-an'offset relation between the entrance and discharge passages while the present invention is directed to an improved relation between the entrance passage and the discharge` passage.

I claim: l l

k1. A draft tube turning vfrom an axial direction. at itsiinlet to a radial directionat its discharge and comprising an entrance passage terminating in anoutwardly flaring bell-mouth formed asa surface of revolution coaxial with the entrance passage and of uniform height above theoor, a discharge passage, a collector passage connecting-'said entrance and discharge passagesV and provided with an upstream wall so disposed beyond the bell-mouth that the bell-mouth extends Whenl theA Draft tube stay vanes 22 may be used or.

upstream without being intersected by the upstream wall, saidwall extending downstream to form the sides of the discharge passage, and the height of the collector passage at its upstream end being not greater than the height of the lower portion of the bell-mouth.

2. A draft tube comprising an entrance passage terminating in a ybell-inoutll formed as a surface of revolution, and a passage leading 'therefrom provided with a substantially vertical upstream wall disposed beyond the bell-mouth Without intersecting the same and having a height at` itsA upstream end not greater nor less than the height of the lower end of the bell-mouth at itsy downstream end.

3. A draft tube comprising an entrance passage terminating` in an outwardly flaring bellmouthformed as a surface of revolution, a collector passage receiving flow from said entrance passages provided with an upstream wall disposed beyond vthe bellmouth without intersecting the same, anda discharge. passage, said wall continuing. downstream to form the sides of' saidV discharge passageandsaid discharge passage having agreater,` depth. along atleast one side thanat its central portion.

4. A draft tube comprising an entrance passage terminating in a bell-mouth, the entrance passage and bell-mouthrbeing formed as a'surface of revolution, a collector4 passage provided with a floor and a substantially vertical upsteram wall disposed beyond the bell-mouth, so` as `not to intersecttheA samegthe. collector passage at its upstreamv end having a height notv greater than the height of the lower end ofthe bellmouth from said iioor, andaconeformed as a surface'ofrevolution concentric with said other surface projecting upwardly from said collector passage into said entrance passage.

5. A draft tube comprising.v anentrance passage terminating in a bell-mouth, the entrance passage and bell-mouth being'formed as a surface of revolution, a collector passage provided with a iloor and an upstreamwall so disposed with respecttothe bell-mouth without intersectingthe samethatthe bell-mouth provides a terminus, for the entrance passage, of substan- Vtially uniform heightfrom the floorv of thecollector passage, and a dischargev passage leading from -said collector passageand. havingrelatively diverging floor and roof, said discharge passage having at least one. point thereof of relatively shallow depthnot greater than the initial radius of thel entrance passage andI said. discharge' passage also having a minimum width at leastthree times its minimum depth.

, LEWIS FERRY MQQDY. 

